So what should you call them? I don't necessary disagree with you, but you did not offer an alternative. When most people you the term "non-believer," they are using it simply to refer to a group of people who are identified by what they do not believe as opposed to what they believe. I agree that "non-believers" often hold deep moral convictions. Nevertheless, religious peoples (Christians, Muslims, Jews, etc.) are identifiable because of their "shared" moral beliefs. If "non-believers" had a shared moral identity, we would refer to them based on that identity. The lack of identity requires us to refer to them in reference to people who have a shared religious beliefs.
My point is: there is no malice behind the term.
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